1
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Buracco S, Döring H, Engelbart S, Singh SP, Paschke P, Whitelaw J, Thomason PA, Paul NR, Tweedy L, Lilla S, McGarry L, Corbyn R, Claydon S, Mietkowska M, Machesky LM, Rottner K, Insall RH. Scar/WAVE drives actin protrusions independently of its VCA domain using proline-rich domains. Curr Biol 2024; 34:4436-4451.e9. [PMID: 39332399 DOI: 10.1016/j.cub.2024.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 04/04/2024] [Accepted: 08/13/2024] [Indexed: 09/29/2024]
Abstract
Cell migration requires the constant modification of cellular shape by reorganization of the actin cytoskeleton. Fine-tuning of this process is critical to ensure new actin filaments are formed only at specific times and in defined regions of the cell. The Scar/WAVE complex is the main catalyst of pseudopod and lamellipodium formation during cell migration. It is a pentameric complex highly conserved through eukaryotic evolution and composed of Scar/WAVE, Abi, Nap1/NCKAP1, Pir121/CYFIP, and HSPC300/Brk1. Its function is usually attributed to activation of the Arp2/3 complex through Scar/WAVE's VCA domain, while other parts of the complex are expected to mediate spatial-temporal regulation and have no direct role in actin polymerization. Here, we show in both B16-F1 mouse melanoma and Dictyostelium discoideum cells that Scar/WAVE without its VCA domain still induces the formation of morphologically normal, actin-rich protrusions, extending at comparable speeds despite a drastic reduction of Arp2/3 recruitment. However, the proline-rich regions in Scar/WAVE and Abi subunits are essential, though either is sufficient for the generation of actin protrusions in B16-F1 cells. We further demonstrate that N-WASP can compensate for the absence of Scar/WAVE's VCA domain and induce lamellipodia formation, but it still requires an intact WAVE complex, even if without its VCA domain. We conclude that the Scar/WAVE complex does more than directly activating Arp2/3, with proline-rich domains playing a central role in promoting actin protrusions. This implies a broader function for the Scar/WAVE complex, concentrating and simultaneously activating many actin-regulating proteins as a lamellipodium-producing core.
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Affiliation(s)
- Simona Buracco
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK.
| | - Hermann Döring
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Stefanie Engelbart
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | | | - Peggy Paschke
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Jamie Whitelaw
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Peter A Thomason
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Nikki R Paul
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Luke Tweedy
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK
| | - Sergio Lilla
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Lynn McGarry
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Ryan Corbyn
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Sophie Claydon
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK
| | - Magdalena Mietkowska
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Laura M Machesky
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany; Braunschweig Integrated Centre of Systems Biology (BRICS), 38106 Braunschweig, Germany
| | - Robert H Insall
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK.
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2
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Wu M, Marchando P, Meyer K, Tang Z, Woolfson DN, Weiner OD. The WAVE complex forms linear arrays at negative membrane curvature to instruct lamellipodia formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.08.600855. [PMID: 39026726 PMCID: PMC11257481 DOI: 10.1101/2024.07.08.600855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Cells generate a wide range of actin-based membrane protrusions for various cell behaviors. These protrusions are organized by different actin nucleation promoting factors. For example, N-WASP controls finger-like filopodia, whereas the WAVE complex controls sheet-like lamellipodia. These different membrane morphologies likely reflect different patterns of nucleator self-organization. N-WASP phase separation has been successfully studied through biochemical reconstitutions, but how the WAVE complex self-organizes to instruct lamellipodia is unknown. Because WAVE complex self-organization has proven refractory to cell-free studies, we leverage in vivo biochemical approaches to investigate WAVE complex organization within its native cellular context. With single molecule tracking and molecular counting, we show that the WAVE complex forms highly regular multilayered linear arrays at the plasma membrane that are reminiscent of a microtubule-like organization. Similar to the organization of microtubule protofilaments in a curved array, membrane curvature is both necessary and sufficient for formation of these WAVE complex linear arrays, though actin polymerization is not. This dependency on negative membrane curvature could explain both the templating of lamellipodia and their emergent behaviors, including barrier avoidance. Our data uncover the key biophysical properties of mesoscale WAVE complex patterning and highlight an integral relationship between NPF self-organization and cell morphogenesis.
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Affiliation(s)
- Muziyue Wu
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute,University of California San Francisco, San Francisco, CA, USA
| | - Paul Marchando
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Kirstin Meyer
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute,University of California San Francisco, San Francisco, CA, USA
| | - Ziqi Tang
- School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA
| | - Derek N Woolfson
- School of Chemistry, University of Bristol, Bristol, UK
- Max Planck-Bristol Centre for Minimal Biology, University of Bristol, Bristol, UK
- School of Biochemistry, University of Bristol, Biomedical Sciences Building, Bristol, UK
- Bristol BioDesign Institute, University of Bristol, Bristol, UK
| | - Orion D Weiner
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute,University of California San Francisco, San Francisco, CA, USA
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3
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Christodoulou A, Tsai JY, Suwankitwat N, Anderson A, Iritani BM. Hem1 inborn errors of immunity: waving goodbye to coordinated immunity in mice and humans. Front Immunol 2024; 15:1402139. [PMID: 39026677 PMCID: PMC11254771 DOI: 10.3389/fimmu.2024.1402139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Accepted: 06/19/2024] [Indexed: 07/20/2024] Open
Abstract
Inborn errors of immunity (IEI) are a group of diseases in humans that typically present as increased susceptibility to infections, autoimmunity, hyperinflammation, allergy, and in some cases malignancy. Among newly identified genes linked to IEIs include 3 independent reports of 9 individuals from 7 independent kindreds with severe primary immunodeficiency disease (PID) and autoimmunity due to loss-of-function mutations in the NCKAP1L gene encoding Hematopoietic protein 1 (HEM1). HEM1 is a hematopoietic cell specific component of the WASp family verprolin homologous (WAVE) regulatory complex (WRC), which acts downstream of multiple immune receptors to stimulate actin nucleation and polymerization of filamentous actin (F-actin). The polymerization and branching of F-actin is critical for creating force-generating cytoskeletal structures which drive most active cellular processes including migration, adhesion, immune synapse formation, and phagocytosis. Branched actin networks at the cell cortex have also been implicated in acting as a barrier to regulate inappropriate vesicle (e.g. cytokine) secretion and spontaneous antigen receptor crosslinking. Given the importance of the actin cytoskeleton in most or all hematopoietic cells, it is not surprising that HEM1 deficient children present with a complex clinical picture that involves overlapping features of immunodeficiency and autoimmunity. In this review, we will provide an overview of what is known about the molecular and cellular functions of HEM1 and the WRC in immune and other cells. We will describe the common clinicopathological features and immunophenotypes of HEM1 deficiency in humans and provide detailed comparative descriptions of what has been learned about Hem1 disruption using constitutive and immune cell-specific mouse knockout models. Finally, we discuss future perspectives and important areas for investigation regarding HEM1 and the WRC.
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Affiliation(s)
- Alexandra Christodoulou
- The Department of Comparative Medicine, University of Washington, Seattle, WA, United States
| | - Julia Y. Tsai
- The Department of Comparative Medicine, University of Washington, Seattle, WA, United States
| | - Nutthakarn Suwankitwat
- The Department of Comparative Medicine, University of Washington, Seattle, WA, United States
- Virology Laboratory, National Institute of Animal Health, Bangkok, Thailand
| | - Andreas Anderson
- The Department of Comparative Medicine, University of Washington, Seattle, WA, United States
| | - Brian M. Iritani
- The Department of Comparative Medicine, University of Washington, Seattle, WA, United States
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4
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Delgado M, Lennon-Duménil AM. How cell migration helps immune sentinels. Front Cell Dev Biol 2022; 10:932472. [PMID: 36268510 PMCID: PMC9577558 DOI: 10.3389/fcell.2022.932472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 09/13/2022] [Indexed: 12/01/2022] Open
Abstract
The immune system relies on the migratory capacity of its cellular components, which must be mobile in order to defend the host from invading micro-organisms or malignant cells. This applies in particular to immune sentinels from the myeloid lineage, i.e. macrophages and dendritic cells. Cell migration is already at work during mammalian early development, when myeloid cell precursors migrate from the yolk sac, an extra embryonic structure, to colonize tissues and form the pool of tissue-resident macrophages. Later, this is accompanied by a migration wave of precursors and monocytes from the bone marrow to secondary lymphoid organs and the peripheral tissues. They differentiate into DCs and monocyte-derived macrophages. During adult life, cell migration endows immune cells with the ability to patrol their environment as well as to circulate between peripheral tissues and lymphoid organs. Hence migration of immune cells is key to building an efficient defense system for an organism. In this review, we will describe how cell migratory capacity regulates the various stages in the life of myeloid cells from development to tissue patrolling, and migration to lymph nodes. We will focus on the role of the actin cytoskeletal machinery and its regulators, and how it contributes to the establishment and function of the immune system.
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5
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Singh SP, Paschke P, Tweedy L, Insall RH. AKT and SGK kinases regulate cell migration by altering Scar/WAVE complex activation and Arp2/3 complex recruitment. Front Mol Biosci 2022; 9:965921. [PMID: 36106016 PMCID: PMC9466652 DOI: 10.3389/fmolb.2022.965921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/28/2022] [Indexed: 11/23/2022] Open
Abstract
Cell polarity and cell migration both depend on pseudopodia and lamellipodia formation. These are regulated by coordinated signaling acting through G-protein coupled receptors and kinases such as PKB/AKT and SGK, as well as the actin cytoskeletal machinery. Here we show that both Dictyostelium PKB and SGK kinases (encoded by pkbA and pkgB) are dispensable for chemotaxis towards folate. However, both are involved in the regulation of pseudopod formation and thus cell motility. Cells lacking pkbA and pkgB showed a substantial drop in cell speed. Actin polymerization is perturbed in pkbA- and reduced in pkgB- and pkbA-/pkgB- mutants. The Scar/WAVE complex, key catalyst of pseudopod formation, is recruited normally to the fronts of all mutant cells (pkbA-, pkgB- and pkbA-/pkgB-), but is unexpectedly unable to recruit the Arp2/3 complex in cells lacking SGK. Consequently, loss of SGK causes a near-complete loss of normal actin pseudopodia, though this can be rescued by overexpression of PKB. Hence both PKB and SGK are required for correct assembly of F-actin and recruitment of the Arp2/3 complex by the Scar/WAVE complex during pseudopodia formation.
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Affiliation(s)
- Shashi Prakash Singh
- CRUK Beatson Institute, Glasgow, United Kingdom
- School of Infection and Immunity, University of Glasgow, Glasgow, United Kingdom
- *Correspondence: Shashi Prakash Singh,
| | | | - Luke Tweedy
- CRUK Beatson Institute, Glasgow, United Kingdom
| | - Robert H. Insall
- CRUK Beatson Institute, Glasgow, United Kingdom
- School of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
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6
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Mijanović L, Weber I. Adhesion of Dictyostelium Amoebae to Surfaces: A Brief History of Attachments. Front Cell Dev Biol 2022; 10:910736. [PMID: 35721508 PMCID: PMC9197732 DOI: 10.3389/fcell.2022.910736] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/13/2022] [Indexed: 12/23/2022] Open
Abstract
Dictyostelium amoebae adhere to extracellular material using similar mechanisms to metazoan cells. Notably, the cellular anchorage loci in Amoebozoa and Metazoa are both arranged in the form of discrete spots and incorporate a similar repertoire of intracellular proteins assembled into multicomponent complexes located on the inner side of the plasma membrane. Surprisingly, however, Dictyostelium lacks integrins, the canonical transmembrane heterodimeric receptors that dominantly mediate adhesion of cells to the extracellular matrix in multicellular animals. In this review article, we summarize the current knowledge about the cell-substratum adhesion in Dictyostelium, present an inventory of the involved proteins, and draw parallels with the situation in animal cells. The emerging picture indicates that, while retaining the basic molecular architecture common to their animal relatives, the adhesion complexes in free-living amoeboid cells have evolved to enable less specific interactions with diverse materials encountered in their natural habitat in the deciduous forest soil. Dissection of molecular mechanisms that underlay short lifetime of the cell-substratum attachments and high turnover rate of the adhesion complexes in Dictyostelium should provide insight into a similarly modified adhesion phenotype that accompanies the mesenchymal-amoeboid transition in tumor metastasis.
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Affiliation(s)
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
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7
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Pipathsouk A, Brunetti RM, Town JP, Graziano BR, Breuer A, Pellett PA, Marchuk K, Tran NHT, Krummel MF, Stamou D, Weiner OD. The WAVE complex associates with sites of saddle membrane curvature. J Cell Biol 2021; 220:e202003086. [PMID: 34096975 PMCID: PMC8185649 DOI: 10.1083/jcb.202003086] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/13/2021] [Accepted: 05/18/2021] [Indexed: 12/30/2022] Open
Abstract
How local interactions of actin regulators yield large-scale organization of cell shape and movement is not well understood. Here we investigate how the WAVE complex organizes sheet-like lamellipodia. Using super-resolution microscopy, we find that the WAVE complex forms actin-independent 230-nm-wide rings that localize to regions of saddle membrane curvature. This pattern of enrichment could explain several emergent cell behaviors, such as expanding and self-straightening lamellipodia and the ability of endothelial cells to recognize and seal transcellular holes. The WAVE complex recruits IRSp53 to sites of saddle curvature but does not depend on IRSp53 for its own localization. Although the WAVE complex stimulates actin nucleation via the Arp2/3 complex, sheet-like protrusions are still observed in ARP2-null, but not WAVE complex-null, cells. Therefore, the WAVE complex has additional roles in cell morphogenesis beyond Arp2/3 complex activation. Our work defines organizing principles of the WAVE complex lamellipodial template and suggests how feedback between cell shape and actin regulators instructs cell morphogenesis.
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Affiliation(s)
- Anne Pipathsouk
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Rachel M. Brunetti
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Jason P. Town
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Brian R. Graziano
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
| | - Artù Breuer
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | | | - Kyle Marchuk
- Department of Pathology and Biological Imaging Development CoLab, University of California, San Francisco, San Francisco, CA
| | - Ngoc-Han T. Tran
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Matthew F. Krummel
- Department of Pathology and Biological Imaging Development CoLab, University of California, San Francisco, San Francisco, CA
| | - Dimitrios Stamou
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Orion D. Weiner
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
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8
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Filić V, Mijanović L, Putar D, Talajić A, Ćetković H, Weber I. Regulation of the Actin Cytoskeleton via Rho GTPase Signalling in Dictyostelium and Mammalian Cells: A Parallel Slalom. Cells 2021; 10:1592. [PMID: 34202767 PMCID: PMC8305917 DOI: 10.3390/cells10071592] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/15/2023] Open
Abstract
Both Dictyostelium amoebae and mammalian cells are endowed with an elaborate actin cytoskeleton that enables them to perform a multitude of tasks essential for survival. Although these organisms diverged more than a billion years ago, their cells share the capability of chemotactic migration, large-scale endocytosis, binary division effected by actomyosin contraction, and various types of adhesions to other cells and to the extracellular environment. The composition and dynamics of the transient actin-based structures that are engaged in these processes are also astonishingly similar in these evolutionary distant organisms. The question arises whether this remarkable resemblance in the cellular motility hardware is accompanied by a similar correspondence in matching software, the signalling networks that govern the assembly of the actin cytoskeleton. Small GTPases from the Rho family play pivotal roles in the control of the actin cytoskeleton dynamics. Indicatively, Dictyostelium matches mammals in the number of these proteins. We give an overview of the Rho signalling pathways that regulate the actin dynamics in Dictyostelium and compare them with similar signalling networks in mammals. We also provide a phylogeny of Rho GTPases in Amoebozoa, which shows a variability of the Rho inventories across different clades found also in Metazoa.
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Affiliation(s)
- Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
| | | | | | | | | | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
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9
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Yang Y, Li D, Chao X, Singh SP, Thomason P, Yan Y, Dong M, Li L, Insall RH, Cai H. Leep1 interacts with PIP3 and the Scar/WAVE complex to regulate cell migration and macropinocytosis. J Cell Biol 2021; 220:212090. [PMID: 33978708 PMCID: PMC8127007 DOI: 10.1083/jcb.202010096] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 03/23/2021] [Accepted: 04/21/2021] [Indexed: 12/20/2022] Open
Abstract
Polarity is essential for diverse functions in many cell types. Establishing polarity requires targeting a network of specific signaling and cytoskeleton molecules to different subregions of the cell, yet the full complement of polarity regulators and how their activities are integrated over space and time to form morphologically and functionally distinct domains remain to be uncovered. Here, by using the model system Dictyostelium and exploiting the characteristic chemoattractant-stimulated translocation of polarly distributed molecules, we developed a proteomic screening approach, through which we identified a leucine-rich repeat domain–containing protein we named Leep1 as a novel polarity regulator. We combined imaging, biochemical, and phenotypic analyses to demonstrate that Leep1 localizes selectively at the leading edge of cells by binding to PIP3, where it modulates pseudopod and macropinocytic cup dynamics by negatively regulating the Scar/WAVE complex. The spatiotemporal coordination of PIP3 signaling, Leep1, and the Scar/WAVE complex provides a cellular mechanism for organizing protrusive structures at the leading edge.
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Affiliation(s)
- Yihong Yang
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xiaoting Chao
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shashi P Singh
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Peter Thomason
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Yonghong Yan
- National Institute of Biological Sciences, Beijing, China
| | - Mengqiu Dong
- National Institute of Biological Sciences, Beijing, China
| | - Lei Li
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Robert H Insall
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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10
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Ghaffari K, Pierce LX, Roufaeil M, Gibson I, Tae K, Sahoo S, Cantrell JR, Andersson O, Lau J, Sakaguchi TF. NCK-associated protein 1 like (nckap1l) minor splice variant regulates intrahepatic biliary network morphogenesis. PLoS Genet 2021; 17:e1009402. [PMID: 33739979 PMCID: PMC8032155 DOI: 10.1371/journal.pgen.1009402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 04/08/2021] [Accepted: 02/09/2021] [Indexed: 11/18/2022] Open
Abstract
Impaired formation of the intrahepatic biliary network leads to cholestatic liver diseases, which are frequently associated with autoimmune disorders. Using a chemical mutagenesis strategy in zebrafish combined with computational network analysis, we screened for novel genes involved in intrahepatic biliary network formation. We positionally cloned a mutation in the nckap1l gene, which encodes a cytoplasmic adaptor protein for the WAVE regulatory complex. The mutation is located in the last exon after the stop codon of the primary splice isoform, only disrupting a previously unannotated minor splice isoform, which indicates that the minor splice isoform is responsible for the intrahepatic biliary network phenotype. CRISPR/Cas9-mediated nckap1l deletion, which disrupts both the primary and minor isoforms, showed the same defects. In the liver of nckap1l mutant larvae, WAVE regulatory complex component proteins are degraded specifically in biliary epithelial cells, which line the intrahepatic biliary network, thus disrupting the actin organization of these cells. We further show that nckap1l genetically interacts with the Cdk5 pathway in biliary epithelial cells. These data together indicate that although nckap1l was previously considered to be a hematopoietic cell lineage-specific protein, its minor splice isoform acts in biliary epithelial cells to regulate intrahepatic biliary network formation.
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Affiliation(s)
- Kimia Ghaffari
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Lain X. Pierce
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Maria Roufaeil
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Isabel Gibson
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Kevin Tae
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Saswat Sahoo
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | - James R. Cantrell
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Olov Andersson
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Jasmine Lau
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Takuya F. Sakaguchi
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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11
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Swaminathan K, Campbell A, Papalazarou V, Jaber-Hijazi F, Nixon C, McGhee E, Strathdee D, Sansom OJ, Machesky LM. The RAC1 Target NCKAP1 Plays a Crucial Role in the Progression of Braf;Pten-Driven Melanoma in Mice. J Invest Dermatol 2021; 141:628-637.e15. [PMID: 32777214 DOI: 10.1016/j.jid.2020.06.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/24/2020] [Accepted: 06/29/2020] [Indexed: 12/30/2022]
Abstract
BRAFV600E is the most common driver mutation in human cutaneous melanoma and is frequently accompanied by loss of the tumor-suppressing phosphatase PTEN. Recent evidence suggests a co-operative role for RAC1 activity in BRAFV600E-driven melanoma progression and drug resistance. However, the underlying molecular mechanisms and the role of RAC1 downstream targets are not well-explored. In this study, we examine the role of the NCKAP1 subunit of the pentameric cytoskeletal SCAR/WAVE complex, a major downstream target of RAC1, in a mouse model of melanoma driven by BRAFV600E;PTEN loss. The SCAR/WAVE complex is the major driver of lamellipodia formation and cell migration downstream of RAC1 and depends on NCKAP1 for its integrity. Targeted deletion of Nckap1 in the melanocyte lineage delayed tumor onset and progression of a mutant Braf;Pten loss‒driven melanoma mouse model. Nckap1-depleted tumors displayed fibrotic stroma with increased collagen deposition concomitant with enhanced immune infiltration. Nckap1 loss slowed proliferation and tumor growth, highlighting a role in cell-cycle progression. Altogether, we propose that NCKAP1-orchestrated actin polymerization is essential for tumor progression and maintenance of tumor tissue integrity in a mutant Braf/Pten loss‒driven mouse model for melanoma.
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Affiliation(s)
- Karthic Swaminathan
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom; Centre for Skin Sciences, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom
| | - Andrew Campbell
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Vassilis Papalazarou
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom; School of Engineering, University of Glasgow, Glasgow, United Kingdom
| | - Farah Jaber-Hijazi
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom; School of Health and Life Sciences, University of the West of Scotland, Paisley, United Kingdom
| | - Colin Nixon
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Ewan McGhee
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | | | - Owen J Sansom
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom; Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Laura M Machesky
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom; Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom.
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12
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van Haastert PJM. Unified control of amoeboid pseudopod extension in multiple organisms by branched F-actin in the front and parallel F-actin/myosin in the cortex. PLoS One 2020; 15:e0243442. [PMID: 33296414 PMCID: PMC7725310 DOI: 10.1371/journal.pone.0243442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023] Open
Abstract
The trajectory of moving eukaryotic cells depends on the kinetics and direction of extending pseudopods. The direction of pseudopods has been well studied to unravel mechanisms for chemotaxis, wound healing and inflammation. However, the kinetics of pseudopod extension-when and why do pseudopods start and stop- is equally important, but is largely unknown. Here the START and STOP of about 4000 pseudopods was determined in four different species, at four conditions and in nine mutants (fast amoeboids Dictyostelium and neutrophils, slow mesenchymal stem cells, and fungus B.d. chytrid with pseudopod and a flagellum). The START of a first pseudopod is a random event with a probability that is species-specific (23%/s for neutrophils). In all species and conditions, the START of a second pseudopod is strongly inhibited by the extending first pseudopod, which depends on parallel filamentous actin/myosin in the cell cortex. Pseudopods extend at a constant rate by polymerization of branched F-actin at the pseudopod tip, which requires the Scar complex. The STOP of pseudopod extension is induced by multiple inhibitory processes that evolve during pseudopod extension and mainly depend on the increasing size of the pseudopod. Surprisingly, no differences in pseudopod kinetics are detectable between polarized, unpolarized or chemotactic cells, and also not between different species except for small differences in numerical values. This suggests that the analysis has uncovered the fundament of cell movement with distinct roles for stimulatory branched F-actin in the protrusion and inhibitory parallel F-actin in the contractile cortex.
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13
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Rijal R, Consalvo KM, Lindsey CK, Gomer RH. An endogenous chemorepellent directs cell movement by inhibiting pseudopods at one side of cells. Mol Biol Cell 2018; 30:242-255. [PMID: 30462573 PMCID: PMC6589559 DOI: 10.1091/mbc.e18-09-0562] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic chemoattraction signal transduction pathways, such as those used by Dictyostelium discoideum to move toward cAMP, use a G protein-coupled receptor to activate multiple conserved pathways such as PI3 kinase/Akt/PKB to induce actin polymerization and pseudopod formation at the front of a cell, and PTEN to localize myosin II to the rear of a cell. Relatively little is known about chemorepulsion. We previously found that AprA is a chemorepellent protein secreted by Dictyostelium cells. Here we used 29 cell lines with disruptions of cAMP and/or AprA signal transduction pathway components, and delineated the AprA chemorepulsion pathway. We find that AprA uses a subset of chemoattraction signal transduction pathways including Ras, protein kinase A, target of rapamycin (TOR), phospholipase A, and ERK1, but does not require the PI3 kinase/Akt/PKB and guanylyl cyclase pathways to induce chemorepulsion. Possibly as a result of not using the PI3 kinase/Akt/PKB pathway and guanylyl cyclases, AprA does not induce actin polymerization or increase the pseudopod formation rate, but rather appears to inhibit pseudopod formation at the side of cells closest to the source of AprA.
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Affiliation(s)
- Ramesh Rijal
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | - Kristen M Consalvo
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | | | - Richard H Gomer
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
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14
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Schaks M, Singh SP, Kage F, Thomason P, Klünemann T, Steffen A, Blankenfeldt W, Stradal TE, Insall RH, Rottner K. Distinct Interaction Sites of Rac GTPase with WAVE Regulatory Complex Have Non-redundant Functions in Vivo. Curr Biol 2018; 28:3674-3684.e6. [PMID: 30393033 PMCID: PMC6264382 DOI: 10.1016/j.cub.2018.10.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/30/2018] [Accepted: 10/01/2018] [Indexed: 12/31/2022]
Abstract
Cell migration often involves the formation of sheet-like lamellipodia generated by branched actin filaments. The branches are initiated when Arp2/3 complex [1] is activated by WAVE regulatory complex (WRC) downstream of small GTPases of the Rac family [2]. Recent structural studies defined two independent Rac binding sites on WRC within the Sra-1/PIR121 subunit of the pentameric WRC [3, 4], but the functions of these sites in vivo have remained unknown. Here we dissect the mechanism of WRC activation and the in vivo relevance of distinct Rac binding sites on Sra-1, using CRISPR/Cas9-mediated gene disruption of Sra-1 and its paralog PIR121 in murine B16-F1 cells combined with Sra-1 mutant rescue. We show that the A site, positioned adjacent to the binding region of WAVE-WCA mediating actin and Arp2/3 complex binding, is the main site for allosteric activation of WRC. In contrast, the D site toward the C terminus is dispensable for WRC activation but required for optimal lamellipodium morphology and function. These results were confirmed in evolutionarily distant Dictyostelium cells. Moreover, the phenotype seen in D site mutants was recapitulated in Rac1 E31 and F37 mutants; we conclude these residues are important for Rac-D site interaction. Finally, constitutively activated WRC was able to induce lamellipodia even after both Rac interaction sites were lost, showing that Rac interaction is not essential for membrane recruitment. Our data establish that physical interaction with Rac is required for WRC activation, in particular through the A site, but is not mandatory for WRC accumulation in the lamellipodium.
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Affiliation(s)
- Matthias Schaks
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Shashi P Singh
- CRUK Beatson Institute, Switchback Road, Glasgow G61 1BD, UK; University of Glasgow Institute of Cancer Sciences, Switchback Road, Glasgow G61 1BD, UK
| | - Frieda Kage
- Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Peter Thomason
- CRUK Beatson Institute, Switchback Road, Glasgow G61 1BD, UK; University of Glasgow Institute of Cancer Sciences, Switchback Road, Glasgow G61 1BD, UK
| | - Thomas Klünemann
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Anika Steffen
- Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Wulf Blankenfeldt
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Theresia E Stradal
- Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Robert H Insall
- CRUK Beatson Institute, Switchback Road, Glasgow G61 1BD, UK; University of Glasgow Institute of Cancer Sciences, Switchback Road, Glasgow G61 1BD, UK.
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
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15
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Fort L, Batista JM, Thomason PA, Spence HJ, Whitelaw JA, Tweedy L, Greaves J, Martin KJ, Anderson KI, Brown P, Lilla S, Neilson MP, Tafelmeyer P, Zanivan S, Ismail S, Bryant DM, Tomkinson NCO, Chamberlain LH, Mastick GS, Insall RH, Machesky LM. Fam49/CYRI interacts with Rac1 and locally suppresses protrusions. Nat Cell Biol 2018; 20:1159-1171. [PMID: 30250061 PMCID: PMC6863750 DOI: 10.1038/s41556-018-0198-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 08/20/2018] [Indexed: 11/09/2022]
Abstract
Actin-based protrusions are reinforced through positive feedback, but it is unclear what restricts their size, or limits positive signals when they retract or split. We identify an evolutionarily conserved regulator of actin-based protrusion: CYRI (CYFIP-related Rac interactor) also known as Fam49 (family of unknown function 49). CYRI binds activated Rac1 via a domain of unknown function (DUF1394) shared with CYFIP, defining DUF1394 as a Rac1-binding module. CYRI-depleted cells have broad lamellipodia enriched in Scar/WAVE, but reduced protrusion-retraction dynamics. Pseudopods induced by optogenetic Rac1 activation in CYRI-depleted cells are larger and longer lived. Conversely, CYRI overexpression suppresses recruitment of active Scar/WAVE to the cell edge, resulting in short-lived, unproductive protrusions. CYRI thus focuses protrusion signals and regulates pseudopod complexity by inhibiting Scar/WAVE-induced actin polymerization. It thus behaves like a 'local inhibitor' as predicted in widely accepted mathematical models, but not previously identified in cells. CYRI therefore regulates chemotaxis, cell migration and epithelial polarization by controlling the polarity and plasticity of protrusions.
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Affiliation(s)
- Loic Fort
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - José Miguel Batista
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | | | | | | | | | - Jennifer Greaves
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | | | - Kurt I Anderson
- CRUK Beatson Institute, Glasgow, UK
- Francis Crick Institute, London, UK
| | | | | | | | | | | | - Shehab Ismail
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - David M Bryant
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Nicholas C O Tomkinson
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, UK
| | - Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | | | - Robert H Insall
- CRUK Beatson Institute, Glasgow, UK.
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK.
| | - Laura M Machesky
- CRUK Beatson Institute, Glasgow, UK.
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK.
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16
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Differential functions of WAVE regulatory complex subunits in the regulation of actin-driven processes. Eur J Cell Biol 2017; 96:715-727. [PMID: 28889942 DOI: 10.1016/j.ejcb.2017.08.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/23/2017] [Accepted: 08/25/2017] [Indexed: 11/22/2022] Open
Abstract
The WAVE regulatory complex (WRC) links upstream Rho-family GTPase signaling to the activation of the ARP2/3 complex in different organisms. WRC-induced and ARP2/3 complex-mediated actin nucleation beneath the plasma membrane is critical for actin assembly in the leading edge to drive efficient cell migration. The WRC is a stable heteropentamer composed of SCAR/WAVE, Abi, Nap, Pir and the small polypeptide Brk1/Hspc300. Functional interference with individual subunits of the complex frequently results in diminished amounts of the remaining polypeptides of the WRC complex, implying the complex to act as molecular entity. However, Abi was also found to associate with mammalian N-WASP, formins, Eps8/SOS1 or VASP, indicating additional functions of individual WRC subunits in eukaryotic cells. To address this issue systematically, we inactivated all WRC subunits, either alone or in combination with VASP in Dictyostelium cells and quantified the protein content of the remaining subunits in respective WRC knockouts. The individual mutants displayed highly differential phenotypes concerning various parameters, including cell morphology, motility, cytokinesis or multicellular development, corroborating the view of additional roles for individual subunits, beyond their established function in WRC-mediated Arp2/3 complex activation. Finally, our data uncover the interaction of the actin polymerase VASP with WRC-embedded Abi to mediate VASP accumulation in cell protrusions, driving efficient cell migration.
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17
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Suess PM, Watson J, Chen W, Gomer RH. Extracellular polyphosphate signals through Ras and Akt to prime Dictyostelium discoideum cells for development. J Cell Sci 2017; 130:2394-2404. [PMID: 28584190 DOI: 10.1242/jcs.203372] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 05/27/2017] [Indexed: 12/21/2022] Open
Abstract
Linear chains of five to hundreds of phosphates called polyphosphate are found in organisms ranging from bacteria to humans, but their function is poorly understood. In Dictyostelium discoideum, polyphosphate is used as a secreted signal that inhibits cytokinesis in an autocrine negative feedback loop. To elucidate how cells respond to this unusual signal, we undertook a proteomic analysis of cells treated with physiological levels of polyphosphate and observed that polyphosphate causes cells to decrease levels of actin cytoskeleton proteins, possibly explaining how polyphosphate inhibits cytokinesis. Polyphosphate also causes proteasome protein levels to decrease, and in both Dictyostelium and human leukemia cells, decreases proteasome activity and cell proliferation. Polyphosphate also induces Dictyostelium cells to begin development by increasing expression of the cell-cell adhesion molecule CsA (also known as CsaA) and causing aggregation, and this effect, as well as the inhibition of proteasome activity, is mediated by Ras and Akt proteins. Surprisingly, Ras and Akt do not affect the ability of polyphosphate to inhibit proliferation, suggesting that a branching pathway mediates the effects of polyphosphate, with one branch affecting proliferation, and the other branch affecting development.
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Affiliation(s)
- Patrick M Suess
- Department of Biology, Texas A&M University, College Station, TX 77843-3474, USA
| | - Jacob Watson
- Department of Biology, Texas A&M University, College Station, TX 77843-3474, USA
| | - Wensheng Chen
- Department of Biology, Texas A&M University, College Station, TX 77843-3474, USA.,Institute of Clinical Pharmacology, Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Hefei 230032, China
| | - Richard H Gomer
- Department of Biology, Texas A&M University, College Station, TX 77843-3474, USA
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18
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Ahmed M, Basheer HA, Ayuso JM, Ahmet D, Mazzini M, Patel R, Shnyder SD, Vinader V, Afarinkia K. Agarose Spot as a Comparative Method for in situ Analysis of Simultaneous Chemotactic Responses to Multiple Chemokines. Sci Rep 2017; 7:1075. [PMID: 28432337 PMCID: PMC5430824 DOI: 10.1038/s41598-017-00949-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/20/2017] [Indexed: 01/07/2023] Open
Abstract
We describe a novel protocol to quantitatively and simultaneously compare the chemotactic responses of cells towards different chemokines. In this protocol, droplets of agarose gel containing different chemokines are applied onto the surface of a Petri dish, and then immersed under culture medium in which cells are suspended. As chemokine molecules diffuse away from the spot, a transient chemoattractant gradient is established across the spots. Cells expressing the corresponding cognate chemokine receptors migrate against this gradient by crawling under the agarose spots towards their centre. We show that this migration is chemokine-specific; meaning that only cells that express the cognate chemokine cell surface receptor, migrate under the spot containing its corresponding chemokine ligand. Furthermore, we show that migration under the agarose spot can be modulated by selective small molecule antagonists present in the cell culture medium.
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Affiliation(s)
- Mohaned Ahmed
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom
| | - Haneen A Basheer
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom
| | - Jose M Ayuso
- Group of Structural Mechanics and Material Modelling, Universidad Zaragoza, Zaragoza, Spain.,Department of Biomedical Engineering, Wisconsin Institutes for Medical Research, and The University of Wisconsin Carbone Cancer Center Madison, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Djevdet Ahmet
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom
| | - Marco Mazzini
- Dipartimento di Scienza e Tecnologia del Farmaco, Universitá Degli Studi di Torino, Via P. Giuria 9, 10125, Torino, Italy
| | - Roshan Patel
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom
| | - Steven D Shnyder
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom
| | - Victoria Vinader
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom
| | - Kamyar Afarinkia
- The Institute of Cancer Therapeutics, University of Bradford, West Yorkshire, BD7 1DP, United Kingdom.
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19
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Afzal TA, Luong LA, Chen D, Zhang C, Yang F, Chen Q, An W, Wilkes E, Yashiro K, Cutillas PR, Zhang L, Xiao Q. NCK Associated Protein 1 Modulated by miRNA-214 Determines Vascular Smooth Muscle Cell Migration, Proliferation, and Neointima Hyperplasia. J Am Heart Assoc 2016; 5:e004629. [PMID: 27927633 PMCID: PMC5210428 DOI: 10.1161/jaha.116.004629] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 10/28/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND MicroRNA miR-214 has been implicated in many biological cellular functions, but the impact of miR-214 and its target genes on vascular smooth muscle cell (VSMC) proliferation, migration, and neointima smooth muscle cell hyperplasia is unknown. METHODS AND RESULTS Expression of miR-214 was closely regulated by different pathogenic stimuli in VSMCs through a transcriptional mechanism and decreased in response to vascular injury. Overexpression of miR-214 in serum-starved VSMCs significantly decreased VSMC proliferation and migration, whereas knockdown of miR-214 dramatically increased VSMC proliferation and migration. Gene and protein biochemical assays, including proteomic analyses, showed that NCK associated protein 1 (NCKAP1)-a major component of the WAVE complex that regulates lamellipodia formation and cell motility-was negatively regulated by miR-214 in VSMCs. Luciferase assays showed that miR-214 substantially repressed wild-type but not the miR-214 binding site mutated version of NCKAP1 3' untranslated region luciferase activity in VSMCs. This result confirmed that NCKAP1 is the functional target of miR-214 in VSMCs. NCKAP1 knockdown in VSMCs recapitulates the inhibitory effects of miR-214 overexpression on actin polymerization, cell migration, and proliferation. Data from cotransfection experiments also revealed that inhibition of NCKAP1 is required for miR-214-mediated lamellipodia formation, cell motility, and growth. Importantly, locally enforced expression of miR-214 in the injured vessels significantly reduced NCKAP1 expression levels, inhibited VSMC proliferation, and prevented neointima smooth muscle cell hyperplasia after injury. CONCLUSIONS We uncovered an important role of miR-214 and its target gene NCKAP1 in modulating VSMC functions and neointima hyperplasia. Our findings suggest that miR-214 represents a potential therapeutic target for vascular diseases.
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Affiliation(s)
- Tayyab Adeel Afzal
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Le Anh Luong
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Dan Chen
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
- Department of Cardiothoracic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Cheng Zhang
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
- Department of Cardiothoracic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Feng Yang
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
- Department of Cardiology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qishan Chen
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
- Department of Cardiology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Weiwei An
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Edmund Wilkes
- Centre for Haemato-Oncology, Barts Cancer Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Kenta Yashiro
- Translational Medicine & Therapeutics, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Pedro R Cutillas
- Centre for Haemato-Oncology, Barts Cancer Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Li Zhang
- Department of Cardiology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qingzhong Xiao
- Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
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20
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Tyrrell BJ, Woodham EF, Spence HJ, Strathdee D, Insall RH, Machesky LM. Loss of strumpellin in the melanocytic lineage impairs the WASH Complex but does not affect coat colour. Pigment Cell Melanoma Res 2016; 29:559-71. [PMID: 27390154 PMCID: PMC5082549 DOI: 10.1111/pcmr.12506] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 07/02/2016] [Indexed: 12/24/2022]
Abstract
The five-subunit WASH complex generates actin networks that participate in endocytic trafficking, migration and invasion in various cell types. Loss of one of the two subunits WASH or strumpellin in mice is lethal, but little is known about their role in mammals in vivo. We explored the role of strumpellin, which has previously been linked to hereditary spastic paraplegia, in the mouse melanocytic lineage. Strumpellin knockout in melanocytes revealed abnormal endocytic vesicle morphology but no impairment of migration in vitro or in vivo and no change in coat colour. Unexpectedly, WASH and filamentous actin could still localize to vesicles in the absence of strumpellin, although the shape and size of vesicles was altered. Blue native PAGE revealed the presence of two distinct WASH complexes, even in strumpellin knockout cells, revealing that the WASH complex can assemble and localize to endocytic compartments in cells in the absence of strumpellin.
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Affiliation(s)
- Benjamin J Tyrrell
- Cancer Research UK Beatson Institute, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Emma F Woodham
- Cancer Research UK Beatson Institute, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Heather J Spence
- Cancer Research UK Beatson Institute, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Douglas Strathdee
- Cancer Research UK Beatson Institute, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Robert H Insall
- Cancer Research UK Beatson Institute, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Laura M Machesky
- Cancer Research UK Beatson Institute, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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21
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Leonhardt H, Gerhardt M, Höppner N, Krüger K, Tarantola M, Beta C. Cell-substrate impedance fluctuations of single amoeboid cells encode cell-shape and adhesion dynamics. Phys Rev E 2016; 93:012414. [PMID: 26871108 DOI: 10.1103/physreve.93.012414] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Indexed: 01/15/2023]
Abstract
We show systematic electrical impedance measurements of single motile cells on microelectrodes. Wild-type cells and mutant strains were studied that differ in their cell-substrate adhesion strength. We recorded the projected cell area by time-lapse microscopy and observed irregular oscillations of the cell shape. These oscillations were correlated with long-term variations in the impedance signal. Superposed to these long-term trends, we observed fluctuations in the impedance signal. Their magnitude clearly correlated with the adhesion strength, suggesting that strongly adherent cells display more dynamic cell-substrate interactions.
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Affiliation(s)
- Helmar Leonhardt
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht Strasse 24/25, 14476 Potsdam, Germany
| | - Matthias Gerhardt
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht Strasse 24/25, 14476 Potsdam, Germany
| | - Nadine Höppner
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
| | - Kirsten Krüger
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht Strasse 24/25, 14476 Potsdam, Germany
| | - Marco Tarantola
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
| | - Carsten Beta
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht Strasse 24/25, 14476 Potsdam, Germany.,Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
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Rho Signaling in Dictyostelium discoideum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:61-181. [DOI: 10.1016/bs.ircmb.2015.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Study of the Chemotactic Response of Multicellular Spheroids in a Microfluidic Device. PLoS One 2015; 10:e0139515. [PMID: 26444904 PMCID: PMC4596573 DOI: 10.1371/journal.pone.0139515] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 09/13/2015] [Indexed: 11/19/2022] Open
Abstract
We report the first application of a microfluidic device to observe chemotactic migration in multicellular spheroids. A microfluidic device was designed comprising a central microchamber and two lateral channels through which reagents can be introduced. Multicellular spheroids were embedded in collagen and introduced to the microchamber. A gradient of fetal bovine serum (FBS) was established across the central chamber by addition of growth media containing serum into one of the lateral channels. We observe that spheroids of oral squamous carcinoma cells OSC–19 invade collectively in the direction of the gradient of FBS. This invasion is more directional and aggressive than that observed for individual cells in the same experimental setup. In contrast to spheroids of OSC–19, U87-MG multicellular spheroids migrate as individual cells. A study of the exposure of spheroids to the chemoattractant shows that the rate of diffusion into the spheroid is slow and thus, the chemoattractant wave engulfs the spheroid before diffusing through it.
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24
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Regulators of Actin Dynamics in Gastrointestinal Tract Tumors. Gastroenterol Res Pract 2015; 2015:930157. [PMID: 26345720 PMCID: PMC4539459 DOI: 10.1155/2015/930157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 07/09/2015] [Accepted: 07/21/2015] [Indexed: 02/07/2023] Open
Abstract
Reorganization of the actin cytoskeleton underlies cell migration in a wide variety of physiological and pathological processes, such as embryonic development, wound healing, and tumor cell invasion. It has been shown that actin assembly and disassembly are precisely regulated by intracellular signaling cascades that respond to changes in the cell microenvironment, ligand binding to surface receptors, or oncogenic transformation of the cell. Actin-nucleating and actin-depolymerizing (ANFs/ADFs) and nucleation-promoting factors (NPFs) regulate cytoskeletal dynamics at the leading edge of migrating cells, thereby modulating cell shape; these proteins facilitate cellular movement and mediate degradation of the surrounding extracellular matrix by secretion of lytic proteases, thus eliminating barriers for tumor cell invasion. Accordingly, expression and activity of these actin-binding proteins have been linked to enhanced metastasis and poor prognosis in a variety of malignancies. In this review, we will summarize what is known about expression patterns and the functional role of actin regulators in gastrointestinal tumors and evaluate first pharmacological approaches to prevent invasion and metastatic dissemination of malignant cells.
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25
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Facette MR, Park Y, Sutimantanapi D, Luo A, Cartwright HN, Yang B, Bennett EJ, Sylvester AW, Smith LG. The SCAR/WAVE complex polarizes PAN receptors and promotes division asymmetry in maize. NATURE PLANTS 2015; 1:14024. [PMID: 27246760 DOI: 10.1038/nplants.2014.24] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/12/2014] [Indexed: 05/03/2023]
Abstract
Pre-mitotic establishment of polarity is a key event in the preparation of mother cells for asymmetric cell divisions that produce daughters of distinct fates, and ensures correct cellular patterning of tissues and eventual organ function. Previous work has shown that two receptor-like kinases, PANGLOSS2 (PAN2) and PAN1, and the small GTPase RHO GTPASE OF PLANTS (ROP) promote mother cell polarity and subsequent division asymmetry in developing maize stomata. PAN proteins become polarized prior to asymmetric cell division, however, the mechanism of this polarization is unknown. Here we show that the SCAR/WAVE regulatory complex, which activates the actin-nucleating ARP2/3 complex, is the first known marker of polarity in this asymmetric division model and is required for PAN polarization. These findings implicate actin, and specifically branched actin networks, in PAN polarization and asymmetric cell division.
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Affiliation(s)
- Michelle R Facette
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116, USA
| | - Yeri Park
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116, USA
| | - Dena Sutimantanapi
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116, USA
| | - Anding Luo
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA
| | - Heather N Cartwright
- Department of Plant Biology, Carnegie Institution of Science, 260 Panama Street, Stanford, California 94305, USA
| | - Bing Yang
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116, USA
| | - Eric J Bennett
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116, USA
| | - Anne W Sylvester
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA
| | - Laurie G Smith
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116, USA
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26
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Zatulovskiy E, Tyson R, Bretschneider T, Kay RR. Bleb-driven chemotaxis of Dictyostelium cells. ACTA ACUST UNITED AC 2014; 204:1027-44. [PMID: 24616222 PMCID: PMC3998804 DOI: 10.1083/jcb.201306147] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Blebs and F-actin-driven pseudopods are alternative ways of extending the leading edge of migrating cells. We show that Dictyostelium cells switch from using predominantly pseudopods to blebs when migrating under agarose overlays of increasing stiffness. Blebs expand faster than pseudopods leaving behind F-actin scars, but are less persistent. Blebbing cells are strongly chemotactic to cyclic-AMP, producing nearly all of their blebs up-gradient. When cells re-orientate to a needle releasing cyclic-AMP, they stereotypically produce first microspikes, then blebs and pseudopods only later. Genetically, blebbing requires myosin-II and increases when actin polymerization or cortical function is impaired. Cyclic-AMP induces transient blebbing independently of much of the known chemotactic signal transduction machinery, but involving PI3-kinase and downstream PH domain proteins, CRAC and PhdA. Impairment of this PI3-kinase pathway results in slow movement under agarose and cells that produce few blebs, though actin polymerization appears unaffected. We propose that mechanical resistance induces bleb-driven movement in Dictyostelium, which is chemotactic and controlled through PI3-kinase.
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Davidson AJ, Ura S, Thomason PA, Kalna G, Insall RH. Abi is required for modulation and stability but not localization or activation of the SCAR/WAVE complex. EUKARYOTIC CELL 2013; 12:1509-16. [PMID: 24036345 PMCID: PMC3837927 DOI: 10.1128/ec.00116-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 09/05/2013] [Indexed: 11/20/2022]
Abstract
The SCAR/WAVE complex drives actin-based protrusion, cell migration, and cell separation during cytokinesis. However, the contribution of the individual complex members to the activity of the whole remains a mystery. This is primarily because complex members depend on one another for stability, which limits the scope for experimental manipulation. Several studies suggest that Abi, a relatively small complex member, connects signaling to SCAR/WAVE complex localization and activation through its polyproline C-terminal tail. We generated a deletion series of the Dictyostelium discoideum Abi to investigate its exact role in regulation of the SCAR complex and identified a minimal fragment that would stabilize the complex. Surprisingly, loss of either the N terminus of Abi or the C-terminal polyproline tail conferred no detectable defect in complex recruitment to the leading edge or the formation of pseudopods. A fragment containing approximately 20% Abi--and none of the sites that couple to known signaling pathways--allowed the SCAR complex to function with normal localization and kinetics. However, expression of N-terminal Abi deletions exacerbated the cytokinesis defect of the Dictyostelium abi mutant, which was earlier shown to be caused by the inappropriate activation of SCAR. This demonstrates, unexpectedly, that Abi does not mediate the SCAR complex's ability to make pseudopods, beyond its role in complex stability. Instead, we propose that Abi has a modulatory role when the SCAR complex is activated through other mechanisms.
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Affiliation(s)
- Andrew J Davidson
- Beatson Institute for Cancer Research, Bearsden, Glasgow, United Kingdom
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Davidson AJ, Insall RH. SCAR/WAVE: A complex issue. Commun Integr Biol 2013; 6:e27033. [PMID: 24753786 PMCID: PMC3984289 DOI: 10.4161/cib.27033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 11/01/2013] [Indexed: 11/19/2022] Open
Abstract
The SCAR/WAVE complex drives the actin polymerisation that underlies protrusion of the front of the cell and thus drives migration. However, it is not understood how the activity of SCAR/WAVE is regulated to generate the infinite range of cellular shape changes observed during cell motility. What are the relative roles of the subunits of the SCAR/WAVE complex? What signaling molecules do they interact with? And how does the complex integrate all this information in order to control the temporal and spatial polymerisation of actin during protrusion formation? Unfortunately, the interdependence of SCAR complex members has made genetic dissection hard. In our recent paper,(1) we describe stabilization of the Dictyostelium SCAR complex by a small fragment of Abi. Here we summarize the main findings and discuss how this approach can help reveal the inner workings of this impenetrable complex.
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Park L, Thomason PA, Zech T, King JS, Veltman DM, Carnell M, Ura S, Machesky LM, Insall RH. Cyclical action of the WASH complex: FAM21 and capping protein drive WASH recycling, not initial recruitment. Dev Cell 2013; 24:169-81. [PMID: 23369714 DOI: 10.1016/j.devcel.2012.12.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 11/02/2012] [Accepted: 12/14/2012] [Indexed: 11/25/2022]
Abstract
WASH causes actin to polymerize on vesicles involved in retrograde traffic and exocytosis. It is found within a regulatory complex, but the physiological roles of the other four members are unknown. Here we present genetic analysis of the subunits' individual functions in Dictyostelium. Mutants in each subunit are completely blocked in exocytosis. All subunits except FAM21 are required to drive actin assembly on lysosomes. Without actin, lysosomes never recycle vacuolar-type H(+)-adenosine triphosphatase (V-ATPase) or neutralize to form postlysosomes. However, in FAM21 knockout lysosomes, WASH generates excessive, dynamic streams of actin. These successfully remove V-ATPase, neutralize, and form huge postlysosomes. The distinction between WASH and FAM21 phenotypes is conserved in human cells. Thus, FAM21 and WASH act at different steps of a cyclical pathway in which FAM21 mediates recycling of the complex back to acidic lysosomes. Recycling is driven by FAM21's interaction with capping protein, which couples the WASH complex to dynamic actin on vesicles.
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Affiliation(s)
- Laura Park
- CR-UK Beatson Institute for Cancer Research, Glasgow University, Switchback Road, Glasgow G61 1BD, UK
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30
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Brzostowski JA, Fey P, Yan J, Isik N, Jin T. The Elmo family forms an ancient group of actin-regulating proteins. Commun Integr Biol 2013; 2:337-40. [PMID: 19721884 DOI: 10.4161/cib.2.4.8549] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 03/18/2009] [Indexed: 01/11/2023] Open
Abstract
The Elmo protein family members are important mediators of small G protein activity, regulating actin-mediated processes such as chemotaxis and engulfment. Until recently,1 Elmo function has not been explored in professional phagocytes such as Dictyostelium discoideum. We discuss the significance of this family with respect to pathways that regulate Rac signaling, we present a comparison of Elmo proteins between representative taxa, and discuss our findings on ElmoA, one of six Elmo proteins found in D. discoideum.
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Affiliation(s)
- Joseph A Brzostowski
- Laboratory of Immunogenetics Imaging Facility; National Institutes of Health; Rockville, MD USA
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31
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Yanagisawa M, Zhang C, Szymanski DB. ARP2/3-dependent growth in the plant kingdom: SCARs for life. FRONTIERS IN PLANT SCIENCE 2013; 4:166. [PMID: 23802001 PMCID: PMC3689024 DOI: 10.3389/fpls.2013.00166] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 05/12/2013] [Indexed: 05/18/2023]
Abstract
In the human experience SCARs (suppressor of cAMP receptors) are permanent reminders of past events, not always based on bad decisions, but always those in which an interplay of opposing forces leaves behind a clear record in the form of some permanent watery mark. During plant morphogenesis, SCARs are important proteins that reflect an unusual evolutionary outcome, in which the plant kingdom relies heavily on this single class of actin-related protein (ARP) 2/3 complex activator to dictate the time and place of actin filament nucleation. This unusually simple arrangement may serve as a permanent reminder that cell shape control in plants is fundamentally different from that of crawling cells in mammals that use the power of actin polymerization to define and maintain cell shape. In plant cells, actin filaments indirectly affect cell shape by determining the transport properties of organelles and cargo molecules that modulate the mechanical properties of the wall. It is becoming increasingly clear that polarized bundles of actin filaments operate at whole cell spatial scales to organize the cytoplasm and dictate the patterns of long-distance intracellular transport and secretion. The number of actin-binding proteins and actin filament nucleators that are known to participate in the process of actin network formation are rapidly increasing. In plants, formins and ARP2/3 are two important actin filament nucleators. This review will focus on ARP2/3, and the apparent reliance of most plant species on the SCAR/WAVE (WASP family verprolin homologous) regulatory complex as the sole pathway for ARP2/3 activation.
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Affiliation(s)
| | - Chunhua Zhang
- Department of Botany and Plant Sciences, University of CaliforniaRiverside, CA, USA
| | - Daniel B. Szymanski
- Department of Agronomy, Purdue UniversityWest Lafayette, IN, USA
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
- *Correspondence: Daniel B. Szymanski, Department of Agronomy, Purdue University, 1150 Lilly Hall of Life Sciences, West Lafayette, IN 47907-1150, USA e-mail:
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32
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Spence HJ, Timpson P, Tang HR, Insall RH, Machesky LM. Scar/WAVE3 contributes to motility and plasticity of lamellipodial dynamics but not invasion in three dimensions. Biochem J 2012; 448:35-42. [PMID: 22909346 PMCID: PMC3929901 DOI: 10.1042/bj20112206] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The Scar (suppressor of cAMP receptor)/WAVE [WASP (Wiskott-Aldrich syndrome protein) verprolin homologous] complex plays a major role in the motility of cells by activating the Arp2/3 complex, which initiates actin branching and drives protrusions. Mammals have three Scar/WAVE isoforms, which show some tissue-specific expression, but their functions have not been differentiated. In the present study we show that depletion of Scar/WAVE3 in the mammalian breast cancer cells MDA-MB-231 results in larger and less dynamic lamellipodia. Scar/WAVE3-depleted cells move more slowly but more persistently on a two-dimensional matrix and they typically only show one lamellipod. However, Scar/WAVE3 appears to have no role in driving invasiveness in a three-dimensional Matrigel™ invasion assay or a three-dimensional collagen invasion assay, suggesting that lamellipodial persistence as seen in two-dimensions is not crucial in three-dimensional environments.
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Affiliation(s)
- Heather J Spence
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Rd., Bearsden, Glasgow G61 1BD, UK
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Veltman DM, King JS, Machesky LM, Insall RH. SCAR knockouts in Dictyostelium: WASP assumes SCAR's position and upstream regulators in pseudopods. J Cell Biol 2012; 198:501-8. [PMID: 22891261 PMCID: PMC3514037 DOI: 10.1083/jcb.201205058] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 07/11/2012] [Indexed: 11/22/2022] Open
Abstract
Under normal conditions, the Arp2/3 complex activator SCAR/WAVE controls actin polymerization in pseudopods, whereas Wiskott-Aldrich syndrome protein (WASP) assembles actin at clathrin-coated pits. We show that, unexpectedly, Dictyostelium discoideum SCAR knockouts could still spread, migrate, and chemotax using pseudopods driven by the Arp2/3 complex. In the absence of SCAR, some WASP relocated from the coated pits to the leading edge, where it behaved with similar dynamics to normal SCAR, forming split pseudopods and traveling waves. Pseudopods colocalized with active Rac, whether driven by WASP or SCAR, though Rac was activated to a higher level in SCAR mutants. Members of the SCAR regulatory complex, in particular PIR121, were not required for WASP regulation. We thus show that WASP is able to respond to all core upstream signals and that regulators coupled through the other members of SCAR's regulatory complex are not essential for pseudopod formation. We conclude that WASP and SCAR can regulate pseudopod actin using similar mechanisms.
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Affiliation(s)
- Douwe M Veltman
- Beatson Institute for Cancer Research, Glasgow G61 1BD, Scotland, UK
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Ura S, Pollitt AY, Veltman DM, Morrice NA, Machesky LM, Insall RH. Pseudopod growth and evolution during cell movement is controlled through SCAR/WAVE dephosphorylation. Curr Biol 2012; 22:553-61. [PMID: 22386315 PMCID: PMC4961229 DOI: 10.1016/j.cub.2012.02.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Revised: 12/22/2011] [Accepted: 02/06/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND SCAR/WAVE is a principal regulator of pseudopod growth in crawling cells. It exists in a stable pentameric complex, which is regulated at multiple levels that are only beginning to be understood. SCAR/WAVE is phosphorylated at multiple sites, but how this affects its biological activity is unclear. Here we show that dephosphorylation of Dictyostelium SCAR controls normal pseudopod dynamics. RESULTS We demonstrate that the C-terminal acidic domain of most Dictyostelium SCAR is basally phosphorylated at four serine residues. A small amount of singly phosphorylated SCAR is also found. SCAR phosphorylation site mutants cannot replace SCAR's role in the pseudopod cycle, though they rescue cell size and growth. Unphosphorylatable SCAR is hyperactive-excessive recruitment to the front results in large pseudopods that fail to bifurcate because they continually grow forward. Conversely, phosphomimetic SCAR is weakly active, causing frequent small, disorganized pseudopods. Even in its regulatory complex, SCAR is normally held inactive by an interaction between the phosphorylated acidic and basic domains. Loss of basic residues complementary to the acidic phosphosites yields a hyperactive protein similar to unphosphorylatable SCAR. CONCLUSIONS Regulated dephosphorylation of a fraction of the cellular SCAR pool is a key step in SCAR activation during pseudopod growth. Phosphorylation increases autoinhibition of the intact complex. Dephosphorylation weakens this interaction and facilitates SCAR activation but also destabilizes the protein. We show that SCAR is specifically dephosphorylated in pseudopods, increasing activation by Rac and lipids and supporting positive feedback of pseudopod growth.
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Affiliation(s)
| | - Alice Y. Pollitt
- Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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35
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Millius A, Watanabe N, Weiner OD. Diffusion, capture and recycling of SCAR/WAVE and Arp2/3 complexes observed in cells by single-molecule imaging. J Cell Sci 2012; 125:1165-76. [PMID: 22349699 DOI: 10.1242/jcs.091157] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The SCAR/WAVE complex drives lamellipodium formation by enhancing actin nucleation by the Arp2/3 complex. Phosphoinositides and Rac activate the SCAR/WAVE complex, but how SCAR/WAVE and Arp2/3 complexes converge at sites of nucleation is unknown. We analyzed the single-molecule dynamics of WAVE2 and p40 (subunits of the SCAR/WAVE and Arp2/3 complexes, respectively) in XTC cells. We observed lateral diffusion of both proteins and captured the transition of p40 from diffusion to network incorporation. These results suggest that a diffusive 2D search facilitates binding of the Arp2/3 complex to actin filaments necessary for nucleation. After nucleation, the Arp2/3 complex integrates into the actin network and undergoes retrograde flow, which results in its broad distribution throughout the lamellipodium. By contrast, the SCAR/WAVE complex is more restricted to the cell periphery. However, with single-molecule imaging, we also observed WAVE2 molecules undergoing retrograde motion. WAVE2 and p40 have nearly identical speeds, lifetimes and sites of network incorporation. Inhibition of actin retrograde flow does not prevent WAVE2 association and disassociation with the membrane but does inhibit WAVE2 removal from the actin cortex. Our results suggest that membrane binding and diffusion expedites the recruitment of nucleation factors to a nucleation site independent of actin assembly, but after network incorporation, ongoing actin polymerization facilitates recycling of SCAR/WAVE and Arp2/3 complexes.
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Affiliation(s)
- Arthur Millius
- Cardiovascular Research Institute and Department of Biochemistry, University of California, San Francisco, CA 94158, USA
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Amarnath S, Kawli T, Mohanty S, Srinivasan N, Nanjundiah V. Pleiotropic roles of a ribosomal protein in Dictyostelium discoideum. PLoS One 2012; 7:e30644. [PMID: 22363460 PMCID: PMC3281849 DOI: 10.1371/journal.pone.0030644] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 12/20/2011] [Indexed: 11/22/2022] Open
Abstract
The cell cycle phase at starvation influences post-starvation differentiation and morphogenesis in Dictyostelium discoideum. We found that when expressed in Saccharomyces cerevisiae, a D. discoideum cDNA that encodes the ribosomal protein S4 (DdS4) rescues mutations in the cell cycle genes cdc24, cdc42 and bem1. The products of these genes affect morphogenesis in yeast via a coordinated moulding of the cytoskeleton during bud site selection. D. discoideum cells that over- or under-expressed DdS4 did not show detectable changes in protein synthesis but displayed similar developmental aberrations whose intensity was graded with the extent of over- or under-expression. This suggested that DdS4 might influence morphogenesis via a stoichiometric effect – specifically, by taking part in a multimeric complex similar to the one involving Cdc24p, Cdc42p and Bem1p in yeast. In support of the hypothesis, the S. cerevisiae proteins Cdc24p, Cdc42p and Bem1p as well as their D. discoideum cognates could be co-precipitated with antibodies to DdS4. Computational analysis and mutational studies explained these findings: a C-terminal domain of DdS4 is the functional equivalent of an SH3 domain in the yeast scaffold protein Bem1p that is central to constructing the bud site selection complex. Thus in addition to being part of the ribosome, DdS4 has a second function, also as part of a multi-protein complex. We speculate that the existence of the second role can act as a safeguard against perturbations to ribosome function caused by spontaneous variations in DdS4 levels.
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Affiliation(s)
- Smita Amarnath
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.
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37
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Bastounis E, Meili R, Alonso-Latorre B, del Álamo JC, Lasheras JC, Firtel RA. The SCAR/WAVE complex is necessary for proper regulation of traction stresses during amoeboid motility. Mol Biol Cell 2011; 22:3995-4003. [PMID: 21900496 PMCID: PMC3204062 DOI: 10.1091/mbc.e11-03-0278] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A combination of traction force and F-actin measurements shows that cells lacking either of the SCAR/WAVE complex proteins SCAR and PIR121 exhibit an altered cell motility cycle and spatiotemporal distribution of tractions stresses, which correlate in magnitude with F-actin levels. Cell migration requires a tightly regulated, spatiotemporal coordination of underlying biochemical pathways. Crucial to cell migration is SCAR/WAVE–mediated dendritic F-actin polymerization at the cell's leading edge. Our goal is to understand the role the SCAR/WAVE complex plays in the mechanics of amoeboid migration. To this aim, we measured and compared the traction stresses exerted by Dictyostelium cells lacking the SCAR/WAVE complex proteins PIR121 (pirA−) and SCAR (scrA−) with those of wild-type cells while they were migrating on flat, elastic substrates. We found that, compared to wild type, both mutant strains exert traction stresses of different strengths that correlate with their F-actin levels. In agreement with previous studies, we found that wild-type cells migrate by repeating a motility cycle in which the cell length and strain energy exerted by the cells on their substrate vary periodically. Our analysis also revealed that scrA− cells display an altered motility cycle with a longer period and a lower migration velocity, whereas pirA− cells migrate in a random manner without implementing a periodic cycle. We present detailed characterization of the traction-stress phenotypes of the various cell lines, providing new insights into the role of F-actin polymerization in regulating cell–substratum interactions and stresses required for motility.
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Affiliation(s)
- Effie Bastounis
- Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, La Jolla, CA 92093, USA
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38
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Davidson AJ, Insall RH. Actin-based motility: WAVE regulatory complex structure reopens old SCARs. Curr Biol 2011; 21:R66-8. [PMID: 21256435 DOI: 10.1016/j.cub.2010.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The SCAR/WAVE complex controls actin polymerization at the leading edges of moving cells, but its mechanism of regulation remains unclear. The recent determination of its crystal structure, and identification of the binding sites for upstream regulators, mean its workings can finally start to be revealed.
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39
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High-resolution X-ray structure of the trimeric Scar/WAVE-complex precursor Brk1. PLoS One 2011; 6:e21327. [PMID: 21701600 PMCID: PMC3119050 DOI: 10.1371/journal.pone.0021327] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 05/30/2011] [Indexed: 01/08/2023] Open
Abstract
The Scar/WAVE-complex links upstream Rho-GTPase signaling to the activation of the conserved Arp2/3-complex. Scar/WAVE-induced and Arp2/3-complex-mediated actin nucleation is crucial for actin assembly in protruding lamellipodia to drive cell migration. The heteropentameric Scar/WAVE-complex is composed of Scar/WAVE, Abi, Nap, Pir and a small polypeptide Brk1/HSPC300, and recent work suggested that free Brk1 serves as a homooligomeric precursor in the assembly of this complex. Here we characterized the Brk1 trimer from Dictyostelium by analytical ultracentrifugation and gelfiltration. We show for the first time its dissociation at concentrations in the nanomolar range as well as an exchange of subunits within different DdBrk1 containing complexes. Moreover, we determined the three-dimensional structure of DdBrk1 at 1.5 Å resolution by X-ray crystallography. Three chains of DdBrk1 are associated with each other forming a parallel triple coiled-coil bundle. Notably, this structure is highly similar to the heterotrimeric α-helical bundle of HSPC300/WAVE1/Abi2 within the human Scar/WAVE-complex. This finding, together with the fact that Brk1 is collectively sandwiched by the remaining subunits and also constitutes the main subunit connecting the triple-coil domain of the HSPC300/WAVE1/Abi2/ heterotrimer to Sra1(Pir1), implies a critical function of this subunit in the assembly process of the entire Scar/WAVE-complex.
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Muinonen-Martin AJ, Veltman DM, Kalna G, Insall RH. An improved chamber for direct visualisation of chemotaxis. PLoS One 2010; 5:e15309. [PMID: 21179457 PMCID: PMC3001854 DOI: 10.1371/journal.pone.0015309] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 11/09/2010] [Indexed: 12/20/2022] Open
Abstract
There has been a growing appreciation over the last decade that chemotaxis plays an important role in cancer migration, invasion and metastasis. Research into the field of cancer cell chemotaxis is still in its infancy and traditional investigative tools have been developed with other cell types and purposes in mind. Direct visualisation chambers are considered the gold standard for investigating the behaviour of cells migrating in a chemotactic gradient. We therefore drew up a list of key attributes that a chemotaxis chamber should have for investigating cancer cell chemotaxis. These include (1) compatibility with thin cover slips for optimal optical properties and to allow use of high numerical aperture (NA) oil immersion objectives; (2) gradients that are relatively stable for at least 24 hours due to the slow migration of cancer cells; (3) gradients of different steepnesses in a single experiment, with defined, consistent directions to avoid the need for complicated analysis; and (4) simple handling and disposability for use with medical samples. Here we describe and characterise the Insall chamber, a novel direct visualisation chamber. We use it to show GFP-lifeact transfected MV3 melanoma cells chemotaxing using a 60x high NA oil immersion objective, which cannot usually be done with other chemotaxis chambers. Linear gradients gave very efficient chemotaxis, contradicting earlier results suggesting that only polynomial gradients were effective. In conclusion, the chamber satisfies our design criteria, most importantly allowing high NA oil immersion microscopy to track chemotaxing cancer cells in detail over 24 hours.
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Park H, Chan MM, Iritani BM. Hem-1: putting the "WAVE" into actin polymerization during an immune response. FEBS Lett 2010; 584:4923-32. [PMID: 20969869 DOI: 10.1016/j.febslet.2010.10.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 09/28/2010] [Accepted: 10/13/2010] [Indexed: 11/28/2022]
Abstract
Most active processes by immune cells including adhesion, migration, and phagocytosis require the coordinated polymerization and depolymerization of filamentous actin (F-actin), which is an essential component of the actin cytoskeleton. This review focuses on a newly characterized hematopoietic cell-specific actin regulatory protein called hematopoietic protein-1 [Hem-1, also known as Nck-associated protein 1-like (Nckap1l or Nap1l)]. Hem-1 is a component of the "WAVE [WASP (Wiskott-Aldrich syndrome protein)-family verprolin homologous protein]" complex, which signals downstream of activated Rac to stimulate F-actin polymerization in response to immuno-receptor signaling. Genetic studies in cell lines and in mice suggest that Hem-1 regulates F-actin polymerization in hematopoietic cells, and may be essential for most active processes dependent on reorganization of the actin cytoskeleton in immune cells.
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Affiliation(s)
- Heon Park
- Department of Comparative Medicine, University of Washington, Seattle, WA 98195-7190, USA.
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Veltman DM, Insall RH. WASP family proteins: their evolution and its physiological implications. Mol Biol Cell 2010; 21:2880-93. [PMID: 20573979 PMCID: PMC2921111 DOI: 10.1091/mbc.e10-04-0372] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
WASP family proteins control actin polymerization by activating the Arp2/3 complex. Several subfamilies exist, but their regulation and physiological roles are not well understood, nor is it even known if all subfamilies have been identified. Our extensive search reveals few novel WASP family proteins. The WASP, WASH, and SCAR/WAVE subfamilies are evolutionarily ancient, with WASH the most universally present, whereas WHAMM/JMY first appears in invertebrates. An unusual Dictyostelium WASP homologue that has lost the WH1 domain has retained its function in clathrin-mediated endocytosis, demonstrating that WASPs can function with a remarkably diverse domain topology. The WASH and SCAR/WAVE regulatory complexes are much more rigidly maintained; their domain topology is highly conserved, and all subunits are present or lost together, showing that the complexes are ancient and functionally interdependent. Finally, each subfamily has a distinctive C motif, indicating that this motif plays a specific role in each subfamily's function, unlike the generic V and A motifs. Our analysis identifies which features are universally conserved, and thus essential, and which are branch-specific modifications. It also shows the WASP family is more widespread and diverse than currently appreciated and unexpectedly biases the physiological role of the Arp2/3 complex toward vesicle traffic.
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Affiliation(s)
- Douwe M Veltman
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
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King JS, Veltman DM, Georgiou M, Baum B, Insall RH. SCAR/WAVE is activated at mitosis and drives myosin-independent cytokinesis. J Cell Sci 2010; 123:2246-55. [PMID: 20530573 DOI: 10.1242/jcs.063735] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Cell division requires the tight coordination of multiple cytoskeletal pathways. The best understood of these involves myosin-II-dependent constriction around the cell equator, but both Dictyostelium and mammalian cells also use a parallel, adhesion-dependent mechanism to generate furrows. We show that the actin nucleation factor SCAR/WAVE is strongly activated during Dictyostelium cytokinesis. This activation localises to large polar protrusions, driving separation of the daughter cells. This continues for 10 minutes after division before the daughter cells revert to normal random motility, indicating that this is a tightly regulated process. We demonstrate that SCAR activity is essential to drive myosin-II-independent cytokinesis, and stabilises the furrow, ensuring symmetrical division. SCAR is also responsible for the generation of MiDASes, mitosis-specific actin-rich adhesions. Loss of SCAR in both Dictyostelium and Drosophila leads to a similar mitotic phenotype, with severe mitotic blebbing, indicating conserved functionality. We also find that the microtubule end-binding protein EB1 is required to restrict SCAR localisation and direct migration. EB1-null cells also exhibit decreased adhesion during mitosis. Our data reveal a spindle-directed signalling pathway that regulates SCAR activity, migration and adhesion at mitosis.
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Affiliation(s)
- Jason S King
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD, UK.
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Insall RH. Understanding eukaryotic chemotaxis: a pseudopod-centred view. Nat Rev Mol Cell Biol 2010; 11:453-8. [PMID: 20445546 DOI: 10.1038/nrm2905] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Current descriptions of eukaryotic chemotaxis and cell movement focus on how extracellular signals (chemoattractants) cause new pseudopods to form. This 'signal-centred' approach is widely accepted but is derived mostly from special cases, particularly steep chemoattractant gradients. I propose a 'pseudopod-centred' explanation, whereby most pseudopods form themselves, without needing exogenous signals, and chemoattractants only bias internal pseudopod dynamics. This reinterpretation of recent data suggests that future research should focus on pseudopod mechanics, not signal processing.
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Affiliation(s)
- Robert H Insall
- Beatson Institute for Cancer Research, Bearsden, Glasgow G61 1BD, UK
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Pollitt AY, Insall RH. WASP and SCAR/WAVE proteins: the drivers of actin assembly. J Cell Sci 2009; 122:2575-8. [PMID: 19625501 DOI: 10.1242/jcs.023879] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Alice Y Pollitt
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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Insall RH, Machesky LM. Actin dynamics at the leading edge: from simple machinery to complex networks. Dev Cell 2009; 17:310-22. [PMID: 19758556 DOI: 10.1016/j.devcel.2009.08.012] [Citation(s) in RCA: 308] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell migration is an essential feature of eukaryotic life, required for processes ranging from feeding and phagoctyosis to development, healing, and immunity. Migration requires the actin cytoskeleton, specifically the localized polymerization of actin filaments underneath the plasma membrane. Here we summarize recent developments in actin biology that particularly affect structures at the leading edge of the cell, including the structure of actin branches, the multiple pathways that lead to cytoskeleton assembly and disassembly, and the role of blebs. Future progress depends on connecting these processes and components to the dynamic behavior of the whole cell in three dimensions.
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Affiliation(s)
- Robert H Insall
- CRUK Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, Scotland.
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King JS, Insall RH. Chemotaxis: finding the way forward with Dictyostelium. Trends Cell Biol 2009; 19:523-30. [PMID: 19733079 DOI: 10.1016/j.tcb.2009.07.004] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 07/03/2009] [Accepted: 07/08/2009] [Indexed: 12/22/2022]
Abstract
Understanding cell migration is centrally important to modern cell biology. However, despite years of study, progress has been hindered by experimental limitations and the complexity of the process. This has led to the popularity of Dictyostelium discoideum, with its experimentally-friendly lifestyle and small, haploid genome, as a tool to dissect the pathways involved in migration. This humble amoeba is now established at the centre of dramatic changes in our understanding of cell movement. In this review we describe the recent reinterpretation of the role of phosphatidylinositol trisphosphate (PIP(3)) and other intracellular messengers that connect signalling and migration, and the transition to models of chemotaxis driven by multiple, intertwined signalling pathways. In shallow gradients, pseudopods are generated with random directions, and we discuss how chemotaxis can operate by biasing this process. Overall we describe how Dictyostelium has the potential to unlock many fundamental questions in the cell motility field.
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Lin TY, Huang CH, Kao HH, Liou GG, Yeh SR, Cheng CM, Chen MH, Pan RL, Juang JL. Abi plays an opposing role to Abl in Drosophila axonogenesis and synaptogenesis. Development 2009; 136:3099-107. [PMID: 19675132 DOI: 10.1242/dev.033324] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Abl tyrosine kinase (Abl) regulates axon guidance by modulating actin dynamics. Abelson interacting protein (Abi), originally identified as a kinase substrate of Abl, also plays a key role in actin dynamics, yet its role with respect to Abl in the developing nervous system remains unclear. Here we show that mutations in abi disrupt axonal patterning in the developing Drosophila central nervous system (CNS). However, reducing abi gene dosage by half substantially rescues Abl mutant phenotypes in pupal lethality, axonal guidance defects and locomotion deficits. Moreover, we show that mutations in Abl increase synaptic growth and spontaneous synaptic transmission frequency at the neuromuscular junction. Double heterozygosity for abi and enabled (ena) also suppresses the synaptic overgrowth phenotypes of Abl mutants, suggesting that Abi acts cooperatively with Ena to antagonize Abl function in synaptogenesis. Intriguingly, overexpressing Abi or Ena alone in cultured cells dramatically redistributed peripheral F-actin to the cytoplasm, with aggregates colocalizing with Abi and/or Ena, and resulted in a reduction in neurite extension. However, co-expressing Abl with Abi or Ena redistributed cytoplasmic F-actin back to the cell periphery and restored bipolar cell morphology. These data suggest that abi and Abl have an antagonistic interaction in Drosophila axonogenesis and synaptogenesis, which possibly occurs through the modulation of F-actin reorganization.
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Affiliation(s)
- Tzu-Yang Lin
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan
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Pollitt AY, Insall RH. Loss of Dictyostelium HSPC300 causes a scar-like phenotype and loss of SCAR protein. BMC Cell Biol 2009; 10:13. [PMID: 19228419 PMCID: PMC2652429 DOI: 10.1186/1471-2121-10-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 02/19/2009] [Indexed: 12/17/2022] Open
Abstract
Background SCAR/WAVE proteins couple signalling to actin polymerization, and are thus fundamental to the formation of pseudopods and lamellipods. They are controlled as part of a five-membered complex that includes the tiny HSPC300 protein. It is not known why SCAR/WAVE is found in such a large assembly, but in Dictyostelium the four larger subunits have different, clearly delineated functions. Results We have generated Dictyostelium mutants in which the HSPC300 gene is disrupted. As has been seen in other regulatory complex mutants, SCAR is lost in these cells, apparently by a post-translational mechanism, though PIR121 levels do not change. HSPC300 knockouts resemble scar mutants in slow migration, roundness, and lack of large pseudopods. However hspc300-colonies on bacteria are larger and more similar to wild type, suggesting that some SCAR function can survive without HSPC300. We find no evidence for functions of HSPC300 outside the SCAR complex. Conclusion HSPC300 is essential for most SCAR complex functions. The phenotype of HSPC300 knockouts is most similar to mutants in scar, not the other members of the SCAR complex, suggesting that HSPC300 acts most directly on SCAR itself.
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Affiliation(s)
- Alice Y Pollitt
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
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Abstract
Actin polymerization provides the driving force for the formation of cell-cell junctions and is mediated by two types of actin nucleators, Arp2/3 and formins. Proteins required for coordinately linking cadherin-mediated adhesion to Arp2/3-dependent versus formin-dependent nucleation have yet to be defined. Here we show a role for Abi, the Abi-binding partner Nap1, and the Nap1-binding protein Sra1 in the regulation of cadherin-dependent adhesion. We found that Abi, which is known to interact with Wave, leading to activation of the Arp2/3 complex, is also capable of interacting with the Diaphanous (Dia)-related formins in the absence of Wave. Knockdown of Abi, Nap1, Sra1, or Dia markedly inhibited cell-cell junctions, whereas knockdown of Wave or Arp2/3 produced mild and transient phenotypes. Dia and Abi colocalized with beta-catenin at cell-cell junctions. Further, Dia and Wave bound to overlapping sites on Abi1, and Wave competed with Dia for Abi1 binding. Notably, an active Dia1 C-terminal fragment that localizes to cell-cell junctions rescued the abnormal junctions induced by depletion of Abi or Nap1 in epithelial cells. These findings uncover a novel link between cadherin-mediated adhesion and the regulation of actin dynamics through the requirement for an Abi/Dia complex for the formation and stability of cell-cell junctions.
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